Abstract: Effects of several factors such as medium, cutting materials and sterilization methods for rapid propagation in vitro on cactus ( Opuntia dillenii ) ‘Milpa Alta’were studied. The results indicated that the optimal mediumfor primary culture was MS + 6-BA 0.6 mg·L^-1 + NAA 1.0 mg·L^-1 + 2 ,4-D 011 mg·L^-1 . Taking cactus fresh stem as explant , a shooting rate of 67 %of latent bud under the spine-base was investigated after 60 days of inoculation on this medium. The appropriate mediumfor multiplication and subculture of shooting were MS + 6-BA 0.1 mg·L^-1 +NAA 1.0 mg·L^-1 + 2 ,4-D 0.2 mg·L^-1 or MS + 6-BA 0.1 mg·L^-1 +NAA 0.5 mg·L^-1 . On this medium shoot multiplication occured at a 5 to 6-fold rate after 50 days. The shoots cultured on the rooting medium of MS + IAA 0.1 mg·L^-1 or MS + IBA 0.1 mg·L^-1 produced rootlets after 10 days. The plantlet upwards of 5 cm height was rooted in sand medium with up to 99 % survival and produced new shoots in the field after 60 days.

Key words: Cactus, Rapid propagation, Multiplication